This is where I had my best meal (and at a good price) in Holland.

When they realized I spoke only English they helped me with the selections, but started off with a free piece of very tasty (lekker) breaded fish. Then had me try their raw herring, with onions. They took a picture of me eating it from the tail! (My guidebook said it was rude to eat this way).
Surprised the onions did not all fall off. Then I tried their smoked mackerel, salmon, and another fish he said swam in a wavy motion.

I joined TripAdvisor just to post a review about this place (it wasn't even listed), and told them I had. TripAdvisor pulled the review for some reason, and I did not here back from them.

Here is their website:

http://vishandelatlantic.nl/vishandel-leiden/

Mainly a to go place, but they have tables outside.

Lonely Planet describes them as having the best raw herring in Holland getting a 10 out of 5.